Air is a mixture of several elements, mainly nitrogen, and
oxygen, and trace amounts of the noble gases.
But this wasn't realised for hundreds of years, and this is
because you can't see these elements.
They're invisible.
But there's one element that has such a beautiful colour in
the gas phase it was actually named because of this.
And it was named by Sir Humphry Davy.
Some experiments and observations on a new
substance which becomes a violet-colored gas by heat, by
Sir Humphry Davy, January 20, 1814.
"A new and very curious substance has recently
occupied the attention of chemists of Paris.
The substance appears as a vapour of a beautiful violet
colour."
Davy notes that when the new substance is exposed to liquid
ammonia a black powder is formed which when dry,
fulminates by the slightest contact or friction.
What he means is, when you touch it, it explodes.
I'm trying to smear some of this rather unpleasant
nitrogen triiodide, but it's deeply unpleasant when dried
and incredibly unstable.
I've just come to check to see how this is doing.
The problem is it needs to dry, and it isn't going to
work until it's dried.
But the longer we leave it, it could go off by itself.
So it's very nervous at the moment.
[EXPLOSION]
[EXPLOSIONS]
Oh.
[INAUDIBLE].
But I felt that force right in my stomach here.
That was a good cloud, wasn't it?
So what we've just seen there is the explosive decomposition
of nitrogen triiodide into nitrogen gas and well, the
purple cloud of iodine vapour.
The explosion has sprayed nitrogen triiodide everywhere,
so I feel rather sorry for whoever is going to be in the
lecture theatre next.
[POPPING NOISES]
Ha, nothing's happening.
This is quite good though.
The suspense is good, isn't it?
Yeah.
Is it going to go?
Oh, your reaction is good.
[MUSIC PLAYING]